iodine/src/dns.c

431 lines
9.7 KiB
C
Raw Normal View History

2006-06-05 16:38:10 +03:00
/*
2009-01-04 01:27:21 +02:00
* Copyright (c) 2006-2009 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
2006-06-05 16:38:10 +03:00
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <time.h>
#include <stdio.h>
#include <stdint.h>
2006-06-05 16:38:10 +03:00
#include <stdlib.h>
2006-06-25 00:11:16 +03:00
#include <stdint.h>
2006-06-05 16:38:10 +03:00
#include <string.h>
#include <ctype.h>
#ifdef WINDOWS32
#include "windows.h"
#else
#include <arpa/nameser.h>
#ifdef DARWIN
#define BIND_8_COMPAT
#include <arpa/nameser_compat.h>
#endif
#include <arpa/inet.h>
#include <err.h>
#endif
#include "dns.h"
2006-08-13 02:24:59 +03:00
#include "encoding.h"
#include "read.h"
2006-06-05 16:38:10 +03:00
2009-09-20 18:11:12 +03:00
#define CHECKLEN(x) if (buflen - (p-buf) < (x)) return 0
int
dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_t datalen)
2006-06-05 17:37:58 +03:00
{
HEADER *header;
short name;
2006-06-05 17:37:58 +03:00
char *p;
int len;
2009-09-20 18:11:12 +03:00
if (buflen < sizeof(HEADER))
return 0;
memset(buf, 0, buflen);
2006-06-05 17:37:58 +03:00
header = (HEADER*)buf;
header->id = htons(q->id);
header->qr = (qr == QR_ANSWER);
2006-06-05 17:37:58 +03:00
header->opcode = 0;
header->aa = (qr == QR_ANSWER);
2006-06-05 17:37:58 +03:00
header->tc = 0;
header->rd = (qr == QR_QUERY);
2006-06-05 17:37:58 +03:00
header->ra = 0;
p = buf + sizeof(HEADER);
switch (qr) {
case QR_ANSWER:
header->ancount = htons(1);
header->qdcount = htons(1);
name = 0xc000 | ((p - buf) & 0x3fff);
2009-09-20 18:11:12 +03:00
/* Question section */
putname(&p, buflen - (p - buf), q->name);
2009-09-20 18:11:12 +03:00
CHECKLEN(4);
putshort(&p, q->type);
putshort(&p, C_IN);
2009-09-20 18:11:12 +03:00
/* Answer section */
CHECKLEN(10);
putshort(&p, name);
2009-09-20 18:11:12 +03:00
if (q->type == T_A)
putshort(&p, T_CNAME); /* answer CNAME to A question */
else
putshort(&p, q->type);
putshort(&p, C_IN);
2009-09-20 18:11:12 +03:00
putlong(&p, 0); /* TTL */
if (q->type == T_CNAME || q->type == T_A || q->type == T_MX)
{
/* data is expected to be like "Hblabla.host.name.com\0" */
char *startp = p;
int namelen;
p += 2; /* skip 2 bytes length */
CHECKLEN(2);
if (q->type == T_MX)
putshort(&p, 10); /* preference */
putname(&p, buflen - (p - buf), data);
CHECKLEN(0);
namelen = p - startp;
namelen -= 2;
putshort(&startp, namelen);
}
else if (q->type == T_TXT)
{
/* TXT has binary or base-X data */
char *startp = p;
int txtlen;
p += 2; /* skip 2 bytes length */
puttxtbin(&p, buflen - (p - buf), data, datalen);
CHECKLEN(0);
txtlen = p - startp;
txtlen -= 2;
putshort(&startp, txtlen);
}
else
{
/* NULL has raw binary data */
datalen = MIN(datalen, buflen - (p - buf));
CHECKLEN(2);
putshort(&p, datalen);
2009-09-20 18:11:12 +03:00
CHECKLEN(datalen);
putdata(&p, data, datalen);
2009-09-20 18:11:12 +03:00
CHECKLEN(0);
}
break;
case QR_QUERY:
2009-09-20 18:11:12 +03:00
/* Note that iodined also uses this for forward queries */
header->qdcount = htons(1);
header->arcount = htons(1);
2009-09-20 18:11:12 +03:00
putname(&p, buflen - (p - buf), data);
2009-09-20 18:11:12 +03:00
CHECKLEN(4);
putshort(&p, q->type);
putshort(&p, C_IN);
2009-09-20 18:11:12 +03:00
/* EDNS0 to advertise maximum response length
(even CNAME/A/MX, 255+255+header would be >512) */
CHECKLEN(11);
2007-02-11 15:54:40 +02:00
putbyte(&p, 0x00); /* Root */
putshort(&p, 0x0029); /* OPT */
putshort(&p, 0x1000); /* Payload size: 4096 */
putshort(&p, 0x0000); /* Higher bits/edns version */
putshort(&p, 0x8000); /* Z */
putshort(&p, 0x0000); /* Data length */
break;
}
len = p - buf;
2006-06-05 17:37:58 +03:00
return len;
}
2006-06-06 16:11:29 +03:00
2008-09-09 23:55:13 +03:00
int
dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomain)
2009-09-20 18:11:12 +03:00
/* Only used when iodined gets an NS type query */
2008-09-09 23:55:13 +03:00
{
HEADER *header;
int len;
short name;
short topname;
short nsname;
char *domain;
int domain_len;
char *p;
2009-09-20 18:11:12 +03:00
if (buflen < sizeof(HEADER))
return 0;
2008-09-09 23:55:13 +03:00
memset(buf, 0, buflen);
header = (HEADER*)buf;
header->id = htons(q->id);
header->qr = 1;
header->opcode = 0;
header->aa = 1;
header->tc = 0;
header->rd = 0;
header->ra = 0;
p = buf + sizeof(HEADER);
header->qdcount = htons(1);
header->ancount = htons(1);
header->arcount = htons(1);
/* pointer to start of name */
name = 0xc000 | ((p - buf) & 0x3fff);
domain = strstr(q->name, topdomain);
if (domain) {
domain_len = (int) (domain - q->name);
} else {
return -1;
}
/* pointer to start of topdomain */
topname = 0xc000 | ((p - buf + domain_len) & 0x3fff);
/* Query section */
2009-09-20 18:11:12 +03:00
putname(&p, buflen - (p - buf), q->name); /* Name */
CHECKLEN(4);
2008-09-09 23:55:13 +03:00
putshort(&p, q->type); /* Type */
putshort(&p, C_IN); /* Class */
/* Answer section */
2009-09-20 18:11:12 +03:00
CHECKLEN(12);
2008-09-09 23:55:13 +03:00
putshort(&p, name); /* Name */
putshort(&p, q->type); /* Type */
putshort(&p, C_IN); /* Class */
2009-09-20 18:11:12 +03:00
putlong(&p, 3600); /* TTL */
2008-09-09 23:55:13 +03:00
putshort(&p, 5); /* Data length */
/* pointer to ns.topdomain */
nsname = 0xc000 | ((p - buf) & 0x3fff);
2009-09-20 18:11:12 +03:00
CHECKLEN(5);
2008-09-09 23:55:13 +03:00
putbyte(&p, 2);
putbyte(&p, 'n');
putbyte(&p, 's');
putshort(&p, topname); /* Name Server */
/* Additional data (A-record of NS server) */
2009-09-20 18:11:12 +03:00
CHECKLEN(12);
2008-09-09 23:55:13 +03:00
putshort(&p, nsname); /* Name Server */
putshort(&p, T_A); /* Type */
putshort(&p, C_IN); /* Class */
2009-09-20 18:11:12 +03:00
putlong(&p, 3600); /* TTL */
2008-09-09 23:55:13 +03:00
putshort(&p, 4); /* Data length */
/* ugly hack to output IP address */
domain = (char *) &q->destination;
2009-09-20 18:11:12 +03:00
CHECKLEN(4);
2008-09-09 23:55:13 +03:00
putbyte(&p, *domain++);
putbyte(&p, *domain++);
putbyte(&p, *domain++);
putbyte(&p, *domain);
len = p - buf;
return len;
}
2009-09-20 18:11:12 +03:00
#undef CHECKLEN
unsigned short
dns_get_id(char *packet, size_t packetlen)
{
HEADER *header;
header = (HEADER*)packet;
if (packetlen < sizeof(HEADER))
return 0;
return ntohs(header->id);
}
2009-09-20 18:11:12 +03:00
#define CHECKLEN(x) if (packetlen - (data-packet) < (x)) return 0
2007-01-28 08:47:51 +02:00
int
dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, size_t packetlen)
2007-01-28 08:47:51 +02:00
{
char name[QUERY_NAME_SIZE];
2007-01-28 08:47:51 +02:00
char rdata[4*1024];
HEADER *header;
short qdcount;
short ancount;
uint32_t ttl;
short class;
short type;
char *data;
short rlen;
int id;
int rv;
rv = 0;
header = (HEADER*)packet;
2007-02-11 15:54:40 +02:00
/* Reject short packets */
if (packetlen < sizeof(HEADER))
return 0;
2007-01-28 08:47:51 +02:00
if (header->qr != qr) {
warnx("header->qr does not match the requested qr");
return -1;
}
2007-01-28 08:47:51 +02:00
data = packet + sizeof(HEADER);
qdcount = ntohs(header->qdcount);
ancount = ntohs(header->ancount);
id = ntohs(header->id);
2009-01-03 22:13:31 +02:00
id = id & 0xFFFF; /* Kill any sign extension */
2007-01-28 08:47:51 +02:00
rlen = 0;
switch (qr) {
case QR_ANSWER:
2009-09-20 18:11:12 +03:00
if(qdcount < 1 || ancount < 1) {
/* We may get both CNAME and A, then ancount=2 */
2007-07-12 01:10:53 +03:00
switch (header->rcode) {
2009-09-20 18:11:12 +03:00
case NOERROR: /* 0 */
if (header->tc)
warnx("Got TRUNCATION as reply: response too long for DNS path");
else
warnx("Got reply without error, but also without question and/or answer");
2007-07-12 01:10:53 +03:00
break;
2009-09-20 18:11:12 +03:00
case FORMERR: /* 1 */
warnx("Got FORMERR as reply: server does not understand our request");
2007-07-12 01:10:53 +03:00
break;
2009-09-20 18:11:12 +03:00
case SERVFAIL: /* 2 */
if (qdcount >= 1
&& packetlen >= sizeof(HEADER) + 2
&& (data[1] == 'r' || data[1] == 'R'))
warnx("Got SERVFAIL as reply on earlier fragsize autoprobe");
else if (qdcount >= 1
&& packetlen >= sizeof(HEADER) + 2
&& (data[1] < '0' || data[1] > '9')
&& (data[1] < 'a' || data[1] > 'f')
&& (data[1] < 'A' || data[1] > 'F')
&& data[1] != 'p' && data[1] != 'P')
warnx("Got SERVFAIL as reply on earlier config setting");
else
warnx("Got SERVFAIL as reply: server failed or recursion timeout");
2007-07-12 01:10:53 +03:00
break;
2009-09-20 18:11:12 +03:00
case NXDOMAIN: /* 3 */
warnx("Got NXDOMAIN as reply: domain does not exist");
break;
case NOTIMP: /* 4 */
warnx("Got NOTIMP as reply: server does not support our request");
break;
case REFUSED: /* 5 */
warnx("Got REFUSED as reply");
2007-07-12 01:10:53 +03:00
break;
default:
2009-09-20 18:11:12 +03:00
warnx("Got RCODE %u as reply", (unsigned int) header->rcode);
2007-07-12 01:10:53 +03:00
break;
}
2007-01-28 08:47:51 +02:00
return -1;
}
if (q != NULL)
q->id = id;
2007-01-28 08:47:51 +02:00
readname(packet, packetlen, &data, name, sizeof(name));
2009-09-20 18:11:12 +03:00
CHECKLEN(4);
2007-01-28 08:47:51 +02:00
readshort(packet, &data, &type);
readshort(packet, &data, &class);
2009-09-20 18:11:12 +03:00
/* Assume that first answer is NULL/CNAME that we wanted */
2007-01-28 08:47:51 +02:00
readname(packet, packetlen, &data, name, sizeof(name));
2009-09-20 18:11:12 +03:00
CHECKLEN(10);
2007-01-28 08:47:51 +02:00
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readlong(packet, &data, &ttl);
readshort(packet, &data, &rlen);
2009-09-20 18:11:12 +03:00
if (type == T_NULL) {
rv = MIN(rlen, sizeof(rdata));
rv = readdata(packet, &data, rdata, rv);
if (rv >= 2 && buf) {
rv = MIN(rv, buflen);
memcpy(buf, rdata, rv);
}
/* "else rv=0;" here? */
2007-01-28 08:47:51 +02:00
}
2009-09-20 18:11:12 +03:00
if ((type == T_CNAME || type == T_MX) && buf) {
if (type == T_MX)
data += 2; /* skip preference */
memset(name, 0, sizeof(name));
readname(packet, packetlen, &data, name, sizeof(name) - 1);
name[sizeof(name)-1] = '\0';
strncpy(buf, name, buflen);
buf[buflen - 1] = '\0';
rv = strlen(buf);
}
if (type == T_TXT && buf) {
rv = readtxtbin(packet, &data, rlen, rdata, sizeof(rdata));
if (rv >= 1) {
rv = MIN(rv, buflen);
memcpy(buf, rdata, rv);
}
}
if (q != NULL)
q->type = type;
2007-01-28 08:47:51 +02:00
break;
case QR_QUERY:
2009-09-20 18:11:12 +03:00
if (qdcount < 1) {
2008-09-10 00:10:48 +03:00
warnx("no question section in name query");
2007-01-28 08:47:51 +02:00
return -1;
}
2009-09-20 18:11:12 +03:00
memset(name, 0, sizeof(name));
readname(packet, packetlen, &data, name, sizeof(name) - 1);
name[sizeof(name)-1] = '\0';
2009-09-20 18:11:12 +03:00
CHECKLEN(4);
2007-01-28 08:47:51 +02:00
readshort(packet, &data, &type);
readshort(packet, &data, &class);
2009-09-20 18:11:12 +03:00
if (q == NULL) {
rv = 0;
break;
}
strncpy(q->name, name, sizeof(q->name));
q->name[sizeof(q->name) - 1] = '\0';
2007-01-28 08:47:51 +02:00
q->type = type;
q->id = id;
rv = strlen(q->name);
2007-01-28 08:47:51 +02:00
break;
}
return rv;
}